The present invention relates generally to devices and methods for analyzing biological fluids. In particular, it relates to the design and use of improved centrifugal rotors which allow delivery of a biological sample or reagent to a cuvette or other chamber in the rotor.
Biological tests of blood plasma and other biological fluids frequently require that fluids be quickly divided into predetermined volumes for analysis in a variety of optical tests or assays. It is also frequently desirable to separate potentially interfering cellular components of the material from the biological fluid prior to testing. Such measurement and separation steps have previously been typically performed by centrifugation to separate, for instance, blood plasma from the cellular components, followed by manual or automated pipetting of predetermined volumes of the blood plasma into separate test wells. Such procedures are labor intensive and time-consuming. As a result, various automated systems and methods have been proposed for providing multiple aliquots of plasma suitable for testing in a more efficient manner.
A major advance in the analysis of biological fluids has been the use of centrifugal rotors. These rotors are designed to measure volumes of a biological fluid, such as blood, remove cellular components, and mix the fluid with an appropriate diluent for optical testing. Typically, the rotors provide a plurality of discrete volumes of sample in separate cuvettes in which the sample is optically analyzed.
When the cuvettes are filling, it is important that individual cuvettes are completely isolated so that bubbles or chemical debris from one cuvette cannot be transferred to another. Simultaneous or parallel filling of the cuvettes is often desired, particularly when chemical analyses depend upon reaction rate.
The rotors capable of performing these functions should be capable of measuring and distributing relatively small volumes of liquid to a large number of cuvettes. The rotor design should be simple and amenable to low-cost manufacturing procedures. In particular, it is desirable for the rotors to be of unitary construction with no separable or movable parts. Liquid measurement and separation steps should be simple and take place in relatively short times. In particular, the methods should require relatively few steps and should be capable of being performed with little or no intervention or manipulations by the operator. It would be particularly desirable if the methods required only rotation of the rotor in order to effect measurement and delivery of the liquid. The present invention addresses these and other needs.